The field of the disclosure relates generally to rotary machines, and more particularly, to a turbine blade having a tip shroud.
At least some known rotary machines include a compressor, a combustor coupled downstream from the compressor, a turbine coupled downstream from the combustor, and a rotor shaft rotatably coupled between the compressor and the turbine. Some known turbines include at least one rotor disk coupled to the rotor shaft, and a plurality of circumferentially-spaced turbine blades that extend outward from each rotor disk to define a stage of the turbine. Each turbine blade includes an airfoil that extends radially outward from a platform towards a turbine casing.
At least some known turbine blades include a shroud that extends from an outer tip end of the airfoil to reduce gas flow leakage between the airfoil and the turbine casing. Additionally, at least some known tip shrouds are coupled to the airfoil tip end at an adjacent fillet region located at the intersection of the airfoil and the shroud. An operational life cycle of at least some turbine blades, such as but not limited to latter stage turbine blades, is limited by creep. Creep is the tendency of a material to deform over time when exposed to a combination of mechanical loading and high temperature. Turbine blade creep rate may be greatly impacted by peak stresses seen in the shroud and the fillet region, in combination with the high operating temperatures often seen at the shroud and the fillet region.